In the history of golf balls, a thread wound golf ball was firstly developed. The thread wound golf ball is obtained by winding thread rubber in a stretched state on a solid or liquid center to form a thread wound core and covering it with a cover of balata, etc. having a thickness of 1 to 2 mm.
A two-piece solid golf ball was subsequently developed, which was composed of a core formed from integrally molded rubber material and a thermoplastic resin cover (e.g. ionomer resin cover) formed on the core. The two-piece solid golf ball is easily produced because of its simple structure, and it has excellent rebound characteristics and excellent durability. Therefore, the two-piece solid golf ball is generally approved of and employed by many golfers, mainly amateur golfers. However, the two-piece solid golf ball exhibits a harder and poorer shot feel at the time of hitting than the thread wound golf ball.
wherein the center point of the core, the surface of the core, the intermediate layer and the cover have a higher hardness which increases in this order, is described in Japanese Patent Kokai publication No. 313643/1997. It is also described that the golf ball has excellent flight performance and durability, and good shot feel. However, in such a golf ball, there has been problems in that the rebound characteristics are degraded and the shot feel is hard and poor, because the intermediate layer is formed from a thermoplastic resin.
In order to provide a two-piece solid golf ball having a shot feel as good as the thread wound golf ball, a soft type two-piece solid golf ball using a softer core has been proposed. However, the use of the soft core adversely affects on rebound characteristics, resulting in a reduction in flight distance and a deterioration in durability.
It has been proposed to place an intermediate layer between the core and the cover of the two-piece solid golf ball to form a three-piece solid golf ball so as to maintain the balance between flight performance and shot feel at the time of hitting (for example, in Japanese Patent Kokai publication Nos. 313643/1997). The three-piece solid golf ball generally occupies the greater part of the golf ball market. The three-piece solid golf ball, when compared with the two-piece golf ball, has better shot feel while maintaining excellent flight performance, because the three-piece golf ball can provide a variety of hardness distribution.
Three-piece solid golf ball comprising a solid core, an intermediate layer and a cover and having a hardness distribution, wherein the center point of the core, the intermediate layer and the cover have higher hardness which increases in this order, is described in Japanese Patent Kokai publication No. 313643/1997. It is also described that the golf ball has excellent flight performance and durability, and good shot feel. However, in the golf ball, there have been problems that the rebound characteristics are degraded and the shot feel is hard and poor, because the intermediate layer is formed from a thermoplastic resin.
A golf ball having such performances has not been obtained in view of the balance of flight performance and shot feel. Therefore, it is required to provide a golf ball having longer flight distance and better shot feel.